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Management of Drainage Water in Illinois

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1 Management of Drainage Water in Illinois
This presentation is intended to help communicate Drainage Water Management concepts and motivation to a general audience: Crop producers Potential NRCS program participants NRCS conservation partners Developed by Illinois NRCS

2 Overview Defining the problem
Introducing drainage water management (DWM) How does it work? Where does it apply? Benefits Planning and applying the practice Available resources Drainage Water Management Illinois

3 A Big Water Quality Issue
Hypoxic Zone or “Dead Zone” Excess of nutrients (primarily nitrogen but also phosphorus and silica) Algal growth  organic matter sinks to bottom, decays, consumes available oxygen Oxygen levels fall lower than 2 mg/l About 90 percent of the nitrate-N discharged via the Mississippi River is from agricultural non-point sources. And more than 50 percent of the nitrate comes from the Upper Mississippi River. What is hypoxia? Hypoxia means "low oxygen." In aquatic ecosystems, low oxygen usually means a concentration of less than 2-3 milligrams of oxygen per liter of water (mg/l). A complete lack of oxygen (0 mg/L) is called anoxia. Since organisms that can live without oxygen (such as some microbes) are the only residents in these areas, they are sometimes called "dead zones". Hypoxia is primarily a problem in estuaries and coastal waters, although it can also be a problem in freshwater lakes. Hypoxic Zone The hypoxic zone in the northern Gulf of Mexico refers to an area along the Louisiana-Texas coast in which water near the bottom of the Gulf contains less than 2 parts per million of dissolved oxygen. Hypoxia can cause fish to leave the area and can cause stress or death to bottom dwelling organisms that can’t move out of the hypoxic zone. Hypoxia is caused primarily by excess nitrogen delivered from the Mississippi River in combination with seasonal stratification of Gulf waters. Nitrogen promotes algal and attendant zooplankton growth. The associated organic matter sinks to the bottom where it decomposes, consuming available oxygen. Stratification of fresh and saline waters prevents oxygen replenishment by mixing of oxygen-rich surface water with oxygen-depleted bottom water. Drainage Water Management Illinois

4 Mississippi River Basin
Average Annual Nitrogen Load in Streams N Load, lbs/acre Less than 1.8 1.8 to 4.4 4.5 to 8.9 9.0 to 16.0 16.1 to 27.1 The image in this slide shows the average annual nitrogen load in streams for (after Goolsby, 1999). The average nitrate loss from agricultural land in the Mississippi River watershed is 2.6 lbs per acre. So you can see that Illinois is a very significant contributor to nitrates in the streams – well above average, and probably the highest in the watershed. We’d like to try and get out of the spotlight here. Watershed Average = 2.6 lbs/acre Drainage Water Management Illinois

5 Tile drained soils vs high nitrate levels
Much of the nation’s water resources are degraded by excessive nutrients. Nutrients are the leading cause (55 percent) of impairment for estuaries and coastal waters, the second leading cause in lakes (32 percent) and rivers (28 percent). Nitrogen from diffuse nonpoint sources is often cited cause of water quality degradation. (T.E. Davenport, USEPA, 1994). Nitrate levels in Illinois surface water are very high. The blue background shows the location of tile drained soils in Illinois. The squares on the map show where elevated nitrate levels in surface water have been observed. The association between high nitrate levels in surface water and tile drainage is clear. So, we need a practice that can help reduce the nitrates coming from tile drainage water. Drainage Water Management Illinois

6 Problem Statement Drainage is needed for economical crop production in many Illinois fields. Tile drainage water is a primary source of nitrate to surface water. Although there seems to be a conflict between needing to drain fields for crop production and the need to reduce nitrates entering surface water, there are actually ways to accomplish both. Let’s consider Drainage Water Management. Drainage Water Management Illinois

7 What is Drainage Water Management?
The process of managing the water table elevation and the timing of water discharges from surface and subsurface agricultural drainage systems. Theory: hold nutrients in field when drainage is not needed for production. If we can “turn off” the tile drainage when it is not needed, the effect will be like turning off the flow of nitrates for that period of time. Drainage water management is all about raising and lowering the water table elevation to control when drainage flow will happen. It also allows the producer to keep the nutrients in the field for a longer period of time (rather than letting them flow away in the tile drain.) And if you’re interested in providing shallow water habitat for wildlife, DWM can help with that too. Drainage Water Management Illinois

8 DWM on a Tile Line Water Level Control Structure Raised Water Table
Solid pipe Ditch First, let’s look at a typical tile outlet. The goal of drainage water management is to drain the field only when necessary to grow crops and do field work. So, there needs to be a way to shut off the drainage when it is not appropriate to drain the field. Typically, this is accomplished by installing a water level control structure on the tile line. The water level control structure is designed according to CPS 587 – Structure For Water Control. Remember, now, the infrastructure work we’re doing on the tile drainage system is essentially adding a way to control the outlet of the drainage system and reduce drainage flow in selected parts of the crop year. When doing DWM, NRCS does not propose to add any surface inlets (underground outlets) to the system, or in any way increase the amount of drainage that is happening out in the field. Drain Water Riser Boards (Adjustable) Drainage Water Management Illinois

9 Zone of Influence (Impacted Area)
Lines labeled 600, 602, and 604 represent elevation contours Now, think about the entire field. Just putting a control structure at the outlet may not be enough. Experience has shown that a single structure will influence the area of the field that is: Contained within the drainage system, and Within the 2 foot contour from the control elevation of the structure (CONTROL ELEVATION = elevation of soil surface at lowest spot in the impacted area) So, it may take more than one structure to properly apply DWM to an entire field.

10 Nutrient Load Reduction
FACT: Less flow from drainage tile  Less nitrates to surface water DWM for subsurface drainage is typically accomplished by rendering the drainage tiles temporarily inoperable. By blocking the tile, the Nitrogen stays in the field (for potential use by the crop.) When the blockage is removed in preparation for field activities, the N has mostly been denitrified, and dissolved P has settled out. In addition, researchers have shown that N concentrations in surface runoff are typically much less than in subsurface drainage flow. Note that controlling the drainage has also been shown to increase both lateral and vertical seepage. Water seeping from the soil profile is typically denitrified when it passes through a reduced zone (where there is sufficient organic carbon) in poorly or very poorly drained soil types. For soils without reduced zones (moderately well drained types, for example), DWM may not be effective in reducing nitrate load to receiving waters, even though it does reduce subsurface drain flow. NO3 + carbon source + bacteria + time = N2 gas Drainage Water Management Illinois

11 Management Prior to field activities ,remove flashboards
During growing season, manage water table to provide capillary water to root zone During fallow season, raise water table (within 6” of the surface) ~10 days prior to tillage, harvest, etc – remove flashboards to drain the field. When removing flash boards, do it gradually to avoid instantaneous high velocity in the tile line. During the growing season, manage the water level to provide capillary water to the root zone (corn: 18”-24” deep). Monitor to avoid prolonged root zone saturation. During fallow season, raise flashboards to within 6” of control elevation (the low spot in the impacted area of the structure). Raise flashboards prior to and during manure application events, to counter the effects of preferential flow paths (soil macropores). Drainage Water Management Illinois

12 Example Management Strategy
Here’s an example schedule for managing the water table in a crop field. The actual dates would vary depending on what crop is being grown and what the weather is like that year. Drainage Water Management Illinois

13 Types of Tile Drain Systems
Patterned drainage Designed to uniformly drain the land Random drainage Mostly in low spots With subsurface drainage systems, all of the action is underground. It’s pretty tough to show pictures of this. Just imagine what might be under the ground surface in this field – what must be taking place in order to make it possible to grow crops. For drainage water management, we’re trying to affect as much of the field as possible. So, the distribution of the drainage tile in the field has a big effect on whether DWM is feasible. Realistically, the drainage tile can only affect the portion of the field within a certain distance from the tile (depending on drain depth and soil type). Random drainage will only affect a small part of the field. DWM is only recommended on fields that have patterned drainage systems. Drainage Water Management Illinois

14 Drainage Management (Parallel System and Flat Topography)
laterals laterals Here is a sketch of a very simple field with a patterned tile drain system. This field is a very good candidate for DWM, because it is very flat. A single water control structure placed at the point where the main line leaves the field will control the water table on the entire field. This is the ideal type of field for DWM. main main Water level control structure Drainage Water Management Illinois

15 Topographic Map with Tile Map Overlay
In order to determine where to put the water control structures and what part(s) of the field are feasible for DWM, we need maps. Specifically, we need topographic, soils, and tile maps, all on the same scale so they can be overlaid. Here is an example of how a tile map system might look with the topographic lines displayed. Notice how tile systems can get complicated in a hurry. This one is pretty simple, with just two main lines exiting the property, and all of the patterned tile is on the same landowner. It’s not always that easy. Look, though, at the topographic map contours. Each of these represents 6 inches of elevation difference. As you can see, there is a fairly good size hill in the left part of the field as we’re looking at the map. Controlling water table on this part of the field will be tough. Remember the 2 foot “zone of influence” we talked about earlier? This hill is more than 2 feet high. If we want to control the water table on the hill, we’d have to install a control structure on each of the laterals. That could be very expensive, not to mention a problem farming around the structures. We just wouldn’t do it.

16 DWM Feasibility and Limitations
Economics Flat topography (0.5% average slope; minimum acre impacted area per structure) Patterned (systematic) subsurface tile system exists Tile map exists Land Use No negative impact on neighbors For economic reasons, it would be ideal to be able to control an entire field with just one water control structure. This is possible only with very flat land. It is also possible to install a DWM system on steeper ground – up to 1% or even higher – but the costs become prohibitive. In addition, it is necessary to have a detailed tile map of the site, to determine where in the field to put control structures, what part of the field can be controlled, and evaluate any potential impacts to neighboring properties. When doing DWM, we need to make sure we aren’t negatively impacting other things that are going on out in the field. For example, we need to pay attention to property boundaries and ensure that neighboring fields are not affected by our DWM activities. Also, if the subsurface tile drainage system is tied in with an underground outlet from a conservation practice like a terrace, for example, we would need to do some critical thinking in order to determine if DWM is still feasible. Drainage Water Management Illinois

17 Tile System Considerations
Goal: Efficiently drain water for field activities as needed, store water during the growing season to relieve summer crop stress, and reduce nitrogen loss during the fallow season. Pattern Tile Design Flat Land – conventional pattern tiling Sloping Land– design for affected zones on the contour If a new tile system is to be installed, consider having the professional tiling contractor design the system with DWM in mind. Think about what would be needed to minimize the number of control structures in a managed drainage system. On flat ground, that would be your typical patterned tile system of mains and laterals. On more sloping ground, you would want the laterals to be placed along the contour rather than straight up and down the hill. Connect those laterals to a submain that runs up the hill. The submain would be where the control structures would go – every 2 feet in elevation. The submain would then connect to a mainline to carry drain flow away. Drainage Water Management Illinois

18 Benefits of DWM As a part of a conservation system, DWM:
Improves water quality Documented 35-81% nitrate load reduction in Illinois Improves soil environment for better vegetative growth Reduces rate of soil organic matter oxidation The variability in the nitrate load reduction is due mostly to varying weather conditions. However, some of the research results are affected by differences in management strategy – timing and water table depth, as well as different topography. As mentioned before, the control structure makes it possible for the grower to manage the water table, which can be a definite benefit in dry years. DWM can also improve the organic matter content. Drainage Water Management Illinois

19 Benefits of DWM As a part of a conservation system, DWM also can:
Reduce wind erosion and particulates (dust) Enable seasonal flooding for wildlife habitat Drainage Water Management Illinois

20 DWM Yield Benefits? Research is inconclusive on yield benefits
Weather is a big factor – yield improvement has good potential in dry years Anecdotal evidence suggests as much as 10-20% yield improvement in some years The Agricultural Drainage Management Coalition recently completed a 5-state Conservation Innovation Grant study on DWM, funded by NRCS. Illinois was included in this study. Their report is online at Other researchers, primarily in the upper Midwest, are also studying crop yields with DWM. It seems that the practice has good potential to improve yields in dry years, but no benefit in years that are wetter than normal. Drainage Water Management Illinois

21 Plan  Design  Install  Manage
Implementation Plan  Design  Install  Manage Conservation plan DWM Plan (CAP 130) is a good start Systems approach: suite of practices Nutrient Management is especially beneficial Infrastructure to facilitate management Implement practices from conservation plan Management (active) Now on to actually planning and applying the practice. One of the big things is that there needs to be a plan. Also, you can’t accomplish DWM without infrastructure, so supporting practices such as CPS 587 are important. The recent Conservation Effects Assessment Program (CEAP) report shows that DWM is much more effective when implemented as a suite of practices rather than just by itself. Nutrient management is especially recommended. Crop rotation, residue management, conservation buffers, and other practices can all work together to improve water quality and other resources both on farm and in the watershed. So, we encourage the development of a Drainage Water Management plan, to be used as part of the producer’s Conservation Plan for the farm. Active management of the structures is critical to success. Having the control structures in place and not using them won’t accomplish the conservation objective. Drainage Water Management Illinois

22 Contents of a DWM Plan ID and location info Objectives
Maps and delineations Control structure summary table Management instructions Signature page The plan is pretty much the all-important document for DWM. Refer to the criteria for CAP 130 for more information. There’s a template DWM plan available from the Illinois online Drainage Guide Drainage Water Management Illinois

23 Potential DWM Acres in Illinois
Flat cropland Likely to be tile drained Minimum15 acre parcels Simplification: land ownership and tile configuration not considered By the Numbers: 24 million cropland acres 10 million drained ~2 million suitable for DWM This map was created by people at the NRCS Geospatial Management Center in Fort Worth, Texas – with help from a team of specialists in many states. Soils and land use data were used to identify the locations most likely to be feasible for drainage water management. The 15 acre minimum was selected because of economics – applying DWM on smaller parcels is less cost effective. About 6 million acres are identified on this map – this is probably overestimated, because the flattest category in the soils data was 1% or flatter. NRCS recommends 0.5% or flatter for drainage water management. However, the overall distribution in the state is about right. Other estimates have put the suitable acres at about 1 – 2 million in Illinois. Another reason for the overestimate is that the study did not consider the effects of land ownership or tile configuration. If there is no tile in the field, then DWM is not feasible or needed. If the tile is there but organized in such a way that it would be prohibitively expensive to do DWM, that would also be a barrier. And if the tile system is shared by multiple landowners and they don’t all want to participate, that could make the system unsuitable for DWM. Drainage Water Management Illinois

24 Available Financial Assistance
Environmental Quality Improvement Program (EQIP) Contact your local NRCS field office for more information Drainage Water Management Illinois

25 NRCS: Helping People Help The Land
USDA is an equal opportunity provider and employer.

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